1. Field of the Invention
The invention relates to the field of plant control and management information systems, and in particular to an integrated plant monitoring and diagnostic system for shared use by the operations, maintenance and engineering departments of a nuclear power plant. The system collects and monitors operating parameter data via sensors, generates prioritized condition reports including present conditions and anticipated impending conditions to be addressed by preventive maintenance or operational changes, and provides users with background technical and historical data that is ranked and cross referenced by related operational systems and related articles of equipment.
2. Prior Art
Various management information systems are known for monitoring and recording process parameters in connection with power generation as well as with industrial processes generally. These systems often are reactive in that they respond to present levels of monitored parameters, or at most respond to present trends to control generation of alarms and the like when a parameter exceeds preset values or threatens to do so. A typical process control system monitors sensed parameters to ensure that they remain within preset limits defined by the programmer of the system. Often the present levels can be displayed graphically to highlight trends.
Another form of management information system is known in connection with scheduling of maintenance procedures. By defining a useful life for each article of equipment among a number of articles which are related or inter-dependent, it is possible to schedule repair, replacement or preventive maintenance operations more efficiently so as to minimize downtime. The idea is to plan replacement or repair of articles of equipment for as late as practicable before an actual failure, preferably using intelligent scheduling procedures to minimize downtime by taking maximum advantage of any downtime. The scheduling system prompts or warns plant personnel to attend to each of the articles which may need attention at or soon after the time at which the maintenance of any particular article becomes critically important.
U.S. Pat. No. 4,908,775--Palusamy et al discloses a cyclic monitoring system which counts down a defined useful life expected for various structures in a nuclear power plant. This system is responsive to operating levels in the plant, and increases the predicted aging rate of plant structures to account for variations in usage including transient loading. A sampling module is provided to detect the current loading of monitored equipment periodically. Transient and steady state operating levels are determined from the sampled data and used to generate a usage factor. Equipment degradation due to fatigue and the like is anticipated by integrating the usage factor over time. Whereas operating levels and transient disturbances are taken into account in assessing the wear on plant equipment, the system can be used to plan maintenance and replacement activities or alternative plant operations, using a more accurate estimation of the useful life of the plant components.
The predictive maintenance system according to Palusamy '775 incorporates both operational data and a defined useful life data indexed to articles of equipment. However, the system is such that it primarily serves only maintenance functions. It would be advantageous to provide a system that benefits operational and engineering departments as well. The present invention is intended to accomplish this by integrating not only information regarding usage and expected useful life, but by further integrating design and technical specifications and historical data into a system that monitors operational levels as well as equipment conditions. This data is provided in a hierarchical data acquisition and processing system providing shared access by the different departments, especially operations, maintenance and engineering. The data is arranged and cross referenced for presentation of meaningful reports for each of the departments.
Nuclear reactors for generation of electric power are heavily instrumented to enable efficient plant operation and to ensure safety. U.S. Pat. No. 4,961,898 Bogard et al discloses a system operable to record and report neutron emission levels in and around the reactor as well as pressure and flow parameters, for accurately assessing the accumulation of stress on the operating structures. U.S. Pat. No. 4,935,195--Palusamy et al similarly attempts to factor corrosion of the coolant flow path structures for assessing the useful life of reactor components.
Typically, monitoring equipment for a nuclear power plant or similar process is associated specifically with a particular structure or operating system of the plant. For example, in Bogard et al the monitoring system is specifically associated with coolant flow structures. In Palusamy '195 the monitoring system is associated with the neutron emissions. For the most part, monitoring systems of this type are dedicated either to safety purposes (e.g., to detect an unsafe condition and to shut down and/or generate alarms automatically), or to operational control (e.g., to control the positions of valves and the like during ongoing plant operation). Routines which accumulate a usage factor for assessing the loading factor on a particular subsystem could use much of the same data which is collected by safety and control instrumentation. However, the prior art fails to provide a fully integrated system that can take full advantage of the available instrumentation.
It would be advantageous to provide such an integrated system which not only monitors various articles of plant equipment, but which also accounts for the interdependence of the subsystems, makes decisions or predictions in view of stored design criteria, and makes all this information available generally to plant personnel. In specifying the subsystems, design criteria and technical specifications were merged under the assumption that the subsystems would operate under certain conditions. Operational conditions such as equipment problems can change the loading level for a given article of equipment or subsystem, and also the loading levels of other articles and subsystems that are related to or interdependent with the given ones. Therefore, the interrelations of the articles or subsystems, their design specifications, their history and their current conditions should all be taken in account when assessing operational conditions and maintenance needs, or when evaluating operations on an engineering level.
It is generally advisable for plant management and/or maintenance personnel to collect any available data regarding the subsystems operating in a plant or in an area of the plant, to coordinate maintenance and repair activities. In this manner, a downtime for work on one or more articles or subsystems can be used for simultaneous work on others. However, a comprehensive calculation and analysis of relevant plant conditions can be lengthy and costly. In a monitoring system where information on operational conditions is only immediately available to the operators (e.g., for safety and/or control purposes), engineers, scientists, maintenance technicians, managers and headquarters staff must collect and analyze much of the same information in planning their activities. Each group tends to collect and analyze data in a manner that is best suited to their own area of concern. Nevertheless, an integrated arrangement is certainly more efficient and useful than one in which the various departments operate substantially independent information systems.
The present invention is intended to integrate diagnostic and predictive instrumentation for a number of interdependent plant systems, for taking advantage of available synergies. Furthermore, safety and control parameters are collected using a data network arrangement that is shared by primary and auxiliary system control and protection groups, plant maintenance groups, plant engineering and management. In order to accomplish this objective, the plant computerized information system is integrated generally with instrument data collection from a variety of sources, and stored design criteria information. The operational parameters are factored together in an integrated diagnostics and monitoring system with technical specifications for condition directed maintenance and aging management. Specific, actionable diagnostic information on equipment condition is developed, including cross referenced selection of background technical data, whereby operations and maintenance decisions can be made more effectively and from a greater base of knowledge.
The diagnostics and maintenance arrangement according to the invention puts control and safety parameter information to use by the engineering and maintenance departments rather than only the operations control personnel. Conversely, the system makes maintenance and engineering information available to operations and safety groups, thus providing various useful lines of communication and data access availability.